An international team of researchers has returned from an expedition onboard the RV Celtic Explorer, mapping a giant submarine canyon off Ireland’s continental shelf. The canyon, named Porcupine Bank Canyon, is deep and covers an area twice the size of Malta, but little is known about it. Until now, the canyon has barely been explored.
“This is a vast submarine canyon system, with near-vertical 700m cliff in places and going as deep as 3000m. You could stack 10 Eiffel towers on top of each other in there. So far from land this canyon is a natural laboratory from which we feel the pulse of the changing Atlantic.” Lead researcher Dr. Aaron Lim of University College Cork (UCC) in Ireland said.
Submarine canyons are a major geomorphic feature. There are hundreds of thousands of large canyons around the world and studies in recent years have considerably increased our understanding of their ecological role, especially in carbon cycle. As humans continue to release carbon dioxide into the atmosphere, it’s crucial for scientists to understand how and where the planet absorbs this potent greenhouse gas.
About quarter of atmospheric carbon dioxide ends up in oceans and underwater canyons transport this carbon to the deep ocean where it cannot get back into the atmosphere.
“Increasing CO2 concentrations in our atmosphere are causing our extreme weather; oceans absorb this CO2 and canyons are a rapid route for pumping it into the deep ocean where it is safely stored away.” Professor Andy Wheeler from UCC’s School of Biological, Earth and Environmental Sciences (BEES) said.
The detailed map of Porcupine Bank Canyon’s boundaries and interior reveals that the upper canyon is full of cold-water coral reefs and mounds. As the ROV ventured deeper into the canyon, it found significant amount of coral debris. There is also exposure of old crustal bedrock in the canyon floor caused by sediment avalanches.
Professor Luis Conti from University of Sao Paulo says.“When we sent down the ROV, we saw that this rim is made of a profusion of cold water corals, which appears to extend for miles along the edge of the canyon.”